Parallel attachment for t-squares



S. H. PARVIN. PARALLEL ATTACHMENT FOR T--SQUARES. APPLICATION FILED FEB-13,1920. RENEWED 1An..12. 1921.

Patented Fe' b ..22, 1921.

f mid/Yr) STANLEY H. rnnvriv, or DAYTON, KENTUCKY.

PARALLEL ATTACHMENT ron r-sauAnEs;

Specification of Letters Patent.

Application filed February 13, 1920, Serial No. 358,380. Renewed January 12, 11921. Serial No. 436,8559.

To all whom it may concern:

Be it known that I, STANLEY I-I. PARVIN,

a citizen of the United States, residing in Dayton, in the county of Campbell and State of Kentucky, have invented certain new and useful Improvements in 1 arallel Attachments for T-Squares, of whlch the following is a specification.

The objects of my invention are to provide means for automatically holding the -T-square in proper position upon the draw;

by sliding the T-square along the end of the drawing board.

My invention consists in the parts and in the combination and arrangement of parts as herein set forth and claimed.

In the drawings, which serve to illustrate my invention:

Figure 1 is a plan-vlew of a drawing board with T-square and triangle placed thereon 7 ready for use in drawing and showing my attachment by which the T-square is held in proper relation to the drawing board, and I Fig. 2 is an end view of the drawing board and T-square held thereon by means of my attachment.

In the embodiment of my invention as illustrated, 1 represents a drawing board; 2 is a screw, eye secured inthe end of the drawing board and to which one end of a T-square holding wire is attached.

The T-square 4 is rovided with a sheave 6 attached to the un er side of the head of the T-square by screw 5.- Holding wire 3 tracks over said sheave and over sheave 7 mounted in screw support 8 fastened to one of the upper corners of the drawing board,

said holding wire tracking over said sheave and being attached to tension spring 9 connected to screw stem 10 which is adjustably connected to adjusting nut 11 mounted in screw bracket 12.

It will thus be seen that my invention is of very simple and economical construction,

comprising few parts which are easilyattached to or detached from a drawing board simply by the attaching or detaching of four screw members,'as the case may be. It will alsobe seen that the T-square 4 may be drawn to the lower edge of the board and that there are no projecting parts of the at- Patented Feb; 22, fear.-

tachment which interfere with the convenience of the draftsman in his work, or which prevent the board from resting upon a table inv a tilted position. It will further be seen, 7

that a given attachmentcan be used upon a small drawing board or one-of large dimensions, it being understood that, when it is applied to a larger board the member 12 will be moved nearer to member 8, allowing more ofthe holding .wire 3 to extend across the end of the board instead of along the upper edge thereof. Likewise, when it is desired to substitute one sizeof T-square for another upon the board, it becomes necessary to adjust thetension fromthe one to V the other and this can be readily accomplished by simply turning the nut 11 to pro vlde for either a larger or smaller T-square as the case may be.

While I have. shown and'illustrated my 1 attachment for use upon the ordinary drawbe understood that I do not desire to be limited to the precise details of construction hereinset forth. 1

What I-claim is new and desire to secure 7 by Letters Patent is:

1. In combination with a drawing board, a T-square, a sheave mounted thereon, a sheave mounted on said drawing board, a

holding-wire attached to said drawing board and tracking said sheaves, a tension member connected to said holding wire, adjusting means connected to said tension means and means for attaching said adjusting means 'to said board.

2. In combination witha drawing board,

av T-square, a sheave mounted thereon, 9.

screw-stem attached to said tension wire, a screw support attached to said drawing board, and an adjusting nut mounted therein, and adapted to engage said screw-stem whereby suitable adjustment may be made.

3. In combination with'a drawing board% 5 a screw-eye attached to near one corner 0 said board, a sheave support mounted near the other corner thereof, and a screw bracket mounted on one edge of sald board,

a T-square, a sheave mounted on the head thereof, a holding-wire attached to said screw-eye and tracking over said sheaves, a

stem for the purposes set forth.

l. In combination with a drawing board,a screw-eye attached to one end thereof, a T- square, a sheave mounted on the lower side of the head of said T-square, a sheave mounted upon the upper edge at the corner of the drawing board, a bracket attached to the upper edge of saiddrawing board, a holding-wire attached to said screw-eye and tracking said sheaves and means for ad justably and automatically regulating the tension of said holding-wire.

STANLEY H. PARVIN.

I screw bracket. and threaded upon said screw- 15' 

